EP0600537A1 - Dispositif d'affichage - Google Patents

Dispositif d'affichage Download PDF

Info

Publication number
EP0600537A1
EP0600537A1 EP93203261A EP93203261A EP0600537A1 EP 0600537 A1 EP0600537 A1 EP 0600537A1 EP 93203261 A EP93203261 A EP 93203261A EP 93203261 A EP93203261 A EP 93203261A EP 0600537 A1 EP0600537 A1 EP 0600537A1
Authority
EP
European Patent Office
Prior art keywords
electrodes
sub
column
display device
pixels
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP93203261A
Other languages
German (de)
English (en)
Inventor
Antonius Gerardus Hendrikus Verhulst
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Koninklijke Philips NV
Original Assignee
Koninklijke Philips Electronics NV
Philips Electronics NV
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Koninklijke Philips Electronics NV, Philips Electronics NV filed Critical Koninklijke Philips Electronics NV
Publication of EP0600537A1 publication Critical patent/EP0600537A1/fr
Withdrawn legal-status Critical Current

Links

Images

Classifications

    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333—Constructional arrangements; Manufacturing methods
    • G02F1/1343—Electrodes
    • G02F1/134309—Electrodes characterised by their geometrical arrangement
    • G02F1/134336—Matrix
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
    • G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
    • G09G3/34—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters by control of light from an independent source
    • G09G3/36—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters by control of light from an independent source using liquid crystals
    • G09G3/3607—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters by control of light from an independent source using liquid crystals for displaying colours or for displaying grey scales with a specific pixel layout, e.g. using sub-pixels
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333—Constructional arrangements; Manufacturing methods
    • G02F1/1343—Electrodes
    • G02F1/134309—Electrodes characterised by their geometrical arrangement
    • G02F1/134345—Subdivided pixels, e.g. for grey scale or redundancy
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/137—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells characterised by the electro-optical or magneto-optical effect, e.g. field-induced phase transition, orientation effect, guest-host interaction or dynamic scattering
    • G02F1/139—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells characterised by the electro-optical or magneto-optical effect, e.g. field-induced phase transition, orientation effect, guest-host interaction or dynamic scattering based on orientation effects in which the liquid crystal remains transparent
    • G02F1/141—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells characterised by the electro-optical or magneto-optical effect, e.g. field-induced phase transition, orientation effect, guest-host interaction or dynamic scattering based on orientation effects in which the liquid crystal remains transparent using ferroelectric liquid crystals
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F2203/00—Function characteristic
    • G02F2203/30—Gray scale
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
    • G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
    • G09G3/2007—Display of intermediate tones
    • G09G3/2074—Display of intermediate tones using sub-pixels

Definitions

  • the invention relates to a display device comprising a bistable electro-optical medium between two supporting plates provided with column electrodes and row electrodes, respectively, which define pixels at the location of their crossings, the column electrodes being divided into column sub-electrodes which define sub-pixels at the location of a row electrode.
  • bistable electro-optical medium is understood to mean any medium which switches between two optical states with a steep transition characteristic (transmission-voltage characteristic curve) or with a hysteresis in this transition characteristic as is used, for example in liquid crystal display devices such as supertwist display devices or ferro-electric display devices.
  • the invention is also applicable to, for example twisted nematic display devices which only switch between the on and off states.
  • the two optical states determine the two extreme transmission levels (possibly together with polarizers and/or reflectors) and hence the extremes of the grey scale. Stages of the grey scale (or grey hues) are understood to mean intermediate transmission levels.
  • a display device of the type mentioned in the opening paragraph is described in EP-A-0 316 774.
  • the display device shown in this application is operated by means of the multiplex drive mode in which in a system of crossing selection or address lines (row electrodes) and data lines (column electrodes) the drive is realised by alternately energizing the address lines, while the information to be written is presented to the data lines.
  • the column electrodes By dividing the column electrodes into sub-electrodes having a different surface area (for example, in accordance with surface ratios of 8:4:2:1) different transmission levels (grey scale stages) can be introduced when using such a display device in transmission.
  • the width of the narrowest sub-column is approximately 1/15 of the total column width.
  • the width of the narrowest sub-column is approximately 5 ⁇ m, which imposes very strict requirements on the tolerances during manufacture.
  • an object of the present invention to provide a display device of the type described in the opening paragraph in which grey levels can be obtained via energization of sub-electrodes while imposing less stringent requirements on said tolerances.
  • a display device is characterized in that at least a part of the surface area of the pixel is opaque at the location of at least one of the column sub-electrodes.
  • two column sub-electrodes have the same width and at least a part of the surface area of the pixel is opaque at the location of at least one of the column sub-electrodes of the same width.
  • the invention is based on the recognition that the quantity of light-transmissive surface area (in the case of operation in transmission) is decisive.
  • dividing for example a column electrode in accordance with a width ratio of 8:4:2:2, in which half the surface area of one of the two narrowest sub-electrodes is light-transmissive, 16 grey levels can also be defined.
  • the width of the narrowest column sub-electrode is now, however, 1/8 of the total column width, which considerably simplifies the manufacture of such a device due to the lower tolerances.
  • Other width ratios of the column sub-electrodes are alternatively possible, for example 8:4:2:3 in which 2/3 of the surface area of the narrowest column sub-electrode but one has been made opaque.
  • a division in accordance with the ratio 1:1:1:1:1:1 may alternatively be chosen in which half the surface area of one of the column sub-electrodes is opaque. This provides the possibility of defining 12 grey levels, while the width of the narrowest column sub-electrode is 1/6 of the total column width. Another possibility is a division in accordance with the ratio 4:2:2:2 in which two of the narrowest sub-electrodes have been made partly opaque (for 50% and 75%, respectively, of their surface areas).
  • the sub-electrodes may be rendered opaque by anodization or by electroless metallization.
  • a portion of a column sub-electrode may be rendered, for example light-absorbing by means of black chromium or by means of absorbing polyimides.
  • the opaque portions of adjacent or subjacent pixels may then be formed as one whole.
  • the number of grey levels in a finished display device can be further increased by providing the device with means for weighted drive.
  • the pixels are activated during ( 1/n+1) st part and (n/n+1) st part of, for example one frame period and brought to one of the two optical states.
  • the optical state weighted over a frame period then determines the grey level.
  • the number of grey levels is thereby raised to n2.
  • Fig. 1 is a diagrammatic plan view of a division of electrodes 1, 2 between which an electro-optical material is present (see also Fig. 2).
  • the electrodes are, for example a row electrode 1 and a column electrode 2 which is divided into sub-electrodes whose widths are in a mutual ratio of 8:4:2:2.
  • a display cell 3 is defined which can entirely or partly change its electro-optical properties by suitably driving the column sub-electrodes.
  • a ferroelectric liquid crystal is chosen as an electro-optical material, or if another bistable switching display element such as a supertwist-nematic liquid crystal display is chosen, such a voltage can be applied to the (sub-)electrodes that a given voltage threshold is exceeded and the transmission state changes locally, for example from light-absorbing to light-transmissive, or vice versa .
  • This behaviour can also be determined by the position of polarizers which may be present.
  • the electrode 2 is divided into sub-electrodes, it is possible to drive only a portion of the display cell 3. For example, upon correct energization of the electrode 1 and the sub-electrode 2 a , the portion 3 a of the display cell is driven so that this portion becomes, for example light-absorbing, while the other portion of the display cell remains light-transmissive.
  • the (sub-)electrodes 1, 2 in a different way, different surface areas of the display cell 3 can be driven so that different light-transmissive/light-absorbing (white/black) ratios are obtained, in other words, different grey levels or transmission levels.
  • Fig. 2 is a diagrammatic cross-section of a part of the device, taken on the line II-II in Fig. 1.
  • the electrodes 1 and 2 are formed as parallel strips of transparent conducting material (for example, indium-tin oxide) on transparent supporting plates or substrates 6, 7 of, for example glass or quartz.
  • the electrode 2 is subdivided into column sub-electrodes 2 a , 2 b , 2 c , 2 d whose widths, as stated, are in a ratio of 8:4:2:2.
  • an orientation layer 8 is provided on one or both substrates.
  • a layer of liquid crystal material 9, in this case a ferroelectric liquid crystal material, is present between the two substrates 6, 7.
  • the device may be used as a display device and will be conventionally provided with polarizers, colour filters and/or mirrors, as well as a source of illumination.
  • the column sub-electrode 2 d has the same width as the column sub-electrode 2 c and a part 10 of its surface area (in this embodiment 50%) has been rendered opaque. It has been assumed that the device is operated in transmission; for a device operated in reflection the part 10 is rendered, for example light-absorbing. In this embodiment the part 10 is rendered opaque by means of a layer of, for example nickel which is deposited on the sub-electrode 2 d by means of selective deposition, for example electroless metallization.
  • the width of the narrowest column sub-electrodes 2 c , 2 d is now approximately 1/8 of the total column width, while this would be approximately 1/15 for a division in accordance with the ratio 8:4:2:1, so that much less stringent requirements are imposed on the photolithographic techniques used during manufacture, while the transmission loss remains limited. Nevertheless grey levels can be realised with the pixel 16 shown (and with weighted drive 256) by driving the column sub-electrodes 2 separately or in combination because their surface areas defining the transmission ratio are in a mutual ratio of 8:4:2:1.
  • Fig. 3 is a diagrammatic plan view of a column subdivision as described with reference to Fig. 1 in which pixels in successive rows are shifted over half their width for obtaining a delta structure of the colour elements R, G and B associated with the pixels.
  • Column sub-electrodes defining, together with an opposite row electrode a pixel in row 11 are now associated with different pixels in row 12.
  • the narrowest column sub-electrodes in row 12 are now situated between the wider column sub-electrodes.
  • the red, blue and green pixels can still acquire the desired intermediate luminance.
  • a black matrix may be arranged between the pixels (and possibly also between sub-pixels), which matrix is denoted by reference numeral 13 in Fig. 3.
  • the parts 10 in this embodiment are common for pixels situated in successive rows. This simplifies manufacture because alignment of the parts 10 with respect to the black matrix 13 between the pixels is not critical in this case.
  • Fig. 4 shows a modification of Fig. 3 in which the column sub-electrodes (six in this embodiment) have the same width within one pixel.
  • 12 transmission levels grey levels
  • the extreme levels are reached by energizing, for example no column sub-electrode upon selection of row 11 (fully light-transmissive with the exception of the area 10) so that in this embodiment the entire effective surface area of pixel 3(R) is light- transmissive, or by energizing all column sub-electrodes so that the complete pixel 3(R) is opaque.
  • Fig. 5 is a diagrammatic plan view of a pixel in which the widths of the column sub-electrodes are in a ratio of 2:1:1:1 and in which 50% and 75% of the surface areas of the column sub-electrodes 2 c and 2 d , respectively, have been rendered opaque.
  • the same number of grey levels can be realised as with the device of Fig. 1, 2 and the narrowest column sub-electrodes now cover no more than approximately 1/5 of the overall column width, this subdivision is at the expense of a large effective transmission or reflection surface area.
  • Fig. 6 shows diagrammatically how a weighted drive is performed in a device with pixels in accordance with Figs. 1, 2.
  • Information 14 to be displayed is converted via a processing unit 15 into information which is stored in one or more registers 16.
  • the row electrodes 1 a , 1 b ..., 1 n are successively selected via a multiplex circuit 17, while information defining the optical state of the pixels is presented to the column sub-electrodes 2 a , 2 b , 2 c , 2 d during a part of each line period.
  • the processing unit 15 includes, for example a picture memory for this purpose.
  • the average optical state throughout one drive period defines the ultimate transmission level (grey level).
  • a total number of 256 levels is now adjustable (including substantially transmissive and opaque).
  • Mutual synchronization takes place via drive signals 18.
  • the display device Since the information is modified after 1/17 part of the drive period, the display device is particularly suitable for fast switching electro-optical media such as ferro-electric liquid crystals.
  • the surface ratios of the sub-pixels in Figs. 1,3 may be more generally be represented as 2 n : 2 n-1 : ...: 2:1 (n ⁇ 3) and 4:2:1, respectively.
  • the ratio of the widths is, for example, 2 n : 2 n-1 : ...: 2:2 and 4:2:2, respectively. It holds for the device of Fig.

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Chemical & Material Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Nonlinear Science (AREA)
  • Engineering & Computer Science (AREA)
  • Mathematical Physics (AREA)
  • Geometry (AREA)
  • Optics & Photonics (AREA)
  • Computer Hardware Design (AREA)
  • Theoretical Computer Science (AREA)
  • Liquid Crystal (AREA)
  • Devices For Indicating Variable Information By Combining Individual Elements (AREA)
EP93203261A 1992-11-30 1993-11-22 Dispositif d'affichage Withdrawn EP0600537A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
EP92203685 1992-11-30
EP92203685 1992-11-30

Publications (1)

Publication Number Publication Date
EP0600537A1 true EP0600537A1 (fr) 1994-06-08

Family

ID=8211080

Family Applications (1)

Application Number Title Priority Date Filing Date
EP93203261A Withdrawn EP0600537A1 (fr) 1992-11-30 1993-11-22 Dispositif d'affichage

Country Status (2)

Country Link
EP (1) EP0600537A1 (fr)
JP (1) JPH06214243A (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0788014A3 (fr) * 1996-02-01 1998-09-09 Canon Kabushiki Kaisha Appareil d'affichage pour l'affichage de niveaux de gris

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0261898A2 (fr) * 1986-09-20 1988-03-30 THORN EMI plc Dispositif d'affichage
EP0379810A2 (fr) * 1988-09-30 1990-08-01 Commissariat A L'energie Atomique Procédé d'affichage de niveaux de gris sur un écran d'affichage du type matriciel

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0261898A2 (fr) * 1986-09-20 1988-03-30 THORN EMI plc Dispositif d'affichage
EP0379810A2 (fr) * 1988-09-30 1990-08-01 Commissariat A L'energie Atomique Procédé d'affichage de niveaux de gris sur un écran d'affichage du type matriciel

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0788014A3 (fr) * 1996-02-01 1998-09-09 Canon Kabushiki Kaisha Appareil d'affichage pour l'affichage de niveaux de gris
US6072555A (en) * 1996-02-01 2000-06-06 Canon Kabushiki Kaisha Display apparatus capable of gradational display

Also Published As

Publication number Publication date
JPH06214243A (ja) 1994-08-05

Similar Documents

Publication Publication Date Title
EP0284134B1 (fr) Méthode de commande d'un dispositif d'affichage à cristal liquide et dispositif d'affichage associé
US5689282A (en) Display device with compensation for stray capacitance
KR100563390B1 (ko) 액정 패널의 구동 장치 및 액정 장치
US5404236A (en) Display device with crossing electrodes with specific ratio for gray scale
USRE33882E (en) Liquid crystal display device
US5602559A (en) Method for driving matrix type flat panel display device
US4764766A (en) Method for driving and liquid crystal display device including dot matrix display part and fixed pattern display port
EP0788014B1 (fr) Appareil d'affichage pour l'affichage de niveaux de gris
US5162932A (en) Method of driving a liquid crystal display with minimum frequency variation of pixel voltage
EP0864913B1 (fr) Modulateur spatial de lumière et dispositif d'affichage
EP0330450A2 (fr) Dispositif d'affichage à cristal liquide
JP3922498B2 (ja) 空間光変調器および表示装置
EP0478043B1 (fr) Ecran de visualisation
KR100276400B1 (ko) 회절 액정 장치
US4772099A (en) Capacitive electrode configuration for liquid crystal displays
US5847684A (en) Display device with mirror-symmetrical pixels
KR970006860B1 (ko) 디스플레이 장치
EP0372637B1 (fr) Dispositif d'affichage
EP0600537A1 (fr) Dispositif d'affichage
KR950001358B1 (ko) 표시장치 및 그의 제어용 집적회로
EP0543447B1 (fr) Dispositif d'affichage

Legal Events

Date Code Title Description
PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

Free format text: ORIGINAL CODE: 0009012

AK Designated contracting states

Kind code of ref document: A1

Designated state(s): DE FR GB IT NL

RAP1 Party data changed (applicant data changed or rights of an application transferred)

Owner name: N.V. PHILIPS' GLOEILAMPENFABRIEKEN

18D Application deemed to be withdrawn

Effective date: 19941209